patch 8.2.3919: Vim9: wrong argument for append() results in two errors

Problem:    Vim9: wrong argument for append() results in two errors.
Solution:   Check did_emsg.  Also for setline().  Adjust the help for
            appendbufline().
diff --git a/src/evalbuffer.c b/src/evalbuffer.c
index 50d26c4..37febe4 100644
--- a/src/evalbuffer.c
+++ b/src/evalbuffer.c
@@ -274,12 +274,14 @@
 f_append(typval_T *argvars, typval_T *rettv)
 {
     linenr_T	lnum;
+    int		did_emsg_before = did_emsg;
 
     if (in_vim9script() && check_for_lnum_arg(argvars, 0) == FAIL)
 	return;
 
     lnum = tv_get_lnum(&argvars[0]);
-    set_buffer_lines(curbuf, lnum, TRUE, &argvars[1], rettv);
+    if (did_emsg == did_emsg_before)
+	set_buffer_lines(curbuf, lnum, TRUE, &argvars[1], rettv);
 }
 
 /*
@@ -290,6 +292,7 @@
 {
     linenr_T	lnum;
     buf_T	*buf;
+    int		did_emsg_before = did_emsg;
 
     if (in_vim9script()
 	    && (check_for_buffer_arg(argvars, 0) == FAIL
@@ -303,7 +306,8 @@
     else
     {
 	lnum = tv_get_lnum_buf(&argvars[1], buf);
-	set_buffer_lines(buf, lnum, append, &argvars[2], rettv);
+	if (did_emsg == did_emsg_before)
+	    set_buffer_lines(buf, lnum, append, &argvars[2], rettv);
     }
 }
 
@@ -502,6 +506,9 @@
     win_T	*curwin_save = NULL;
     tabpage_T	*tp;
     win_T	*wp;
+    int		did_emsg_before = did_emsg;
+
+    rettv->vval.v_number = 1;	// FAIL by default
 
     if (in_vim9script()
 	    && (check_for_buffer_arg(argvars, 0) == FAIL
@@ -511,13 +518,12 @@
 
     buf = tv_get_buf(&argvars[0], FALSE);
     if (buf == NULL)
-    {
-	rettv->vval.v_number = 1; // FAIL
 	return;
-    }
     is_curbuf = buf == curbuf;
 
     first = tv_get_lnum_buf(&argvars[1], buf);
+    if (did_emsg > did_emsg_before)
+	return;
     if (argvars[2].v_type != VAR_UNKNOWN)
 	last = tv_get_lnum_buf(&argvars[2], buf);
     else
@@ -525,10 +531,7 @@
 
     if (buf->b_ml.ml_mfp == NULL || first < 1
 			   || first > buf->b_ml.ml_line_count || last < first)
-    {
-	rettv->vval.v_number = 1;	// FAIL
 	return;
-    }
 
     if (!is_curbuf)
     {
@@ -577,6 +580,7 @@
 	curbuf = curbuf_save;
 	curwin = curwin_save;
     }
+    rettv->vval.v_number = 0; // OK
 }
 
 /*
@@ -780,6 +784,7 @@
     linenr_T	lnum = 1;
     linenr_T	end = 1;
     buf_T	*buf;
+    int		did_emsg_before = did_emsg;
 
     if (in_vim9script()
 	    && (check_for_buffer_arg(argvars, 0) == FAIL
@@ -791,6 +796,8 @@
     if (buf != NULL)
     {
 	lnum = tv_get_lnum_buf(&argvars[1], buf);
+	if (did_emsg > did_emsg_before)
+	    return;
 	if (argvars[2].v_type == VAR_UNKNOWN)
 	    end = lnum;
 	else
@@ -852,12 +859,14 @@
 f_setline(typval_T *argvars, typval_T *rettv)
 {
     linenr_T	lnum;
+    int		did_emsg_before = did_emsg;
 
     if (in_vim9script() && check_for_lnum_arg(argvars, 0) == FAIL)
 	return;
 
     lnum = tv_get_lnum(&argvars[0]);
-    set_buffer_lines(curbuf, lnum, FALSE, &argvars[1], rettv);
+    if (did_emsg == did_emsg_before)
+	set_buffer_lines(curbuf, lnum, FALSE, &argvars[1], rettv);
 }
 #endif  // FEAT_EVAL
 
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index d528b71..978ceb0 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -183,7 +183,8 @@
   CheckDefAndScriptFailure(['append([1], "x")'], ['E1013: Argument 1: type mismatch, expected string but got list<number>', 'E1220: String or Number required for argument 1'])
   CheckDefExecAndScriptFailure(['append("", "x")'], 'E1209: Invalid value for a line number')
   CheckDefExecAndScriptFailure(['append(".a", "x")'], 'E1209: Invalid value for a line number')
-  CheckDefExecAndScriptFailure(['append("''aa", "x")'], 'E1209: Invalid value for a line number')
+  # only get one error
+  assert_fails('append("''aa", "x")', ['E1209: Invalid value for a line number: "''aa"', 'E1209:'])
   CheckDefExecAndScriptFailure(['append(-1, "x")'], 'E966: Invalid line number: -1')
   bwipe!
 enddef
@@ -203,6 +204,8 @@
   CheckDefAndScriptFailure(['appendbufline([1], 1, "x")'], ['E1013: Argument 1: type mismatch, expected string but got list<number>', 'E1220: String or Number required for argument 1'])
   CheckDefAndScriptFailure(['appendbufline(1, [1], "x")'], ['E1013: Argument 2: type mismatch, expected string but got list<number>', 'E1220: String or Number required for argument 2'])
   CheckDefExecAndScriptFailure(['appendbufline(' .. bnum .. ', -1, "x")'], 'E966: Invalid line number: -1')
+  CheckDefExecAndScriptFailure(['appendbufline(' .. bnum .. ', "$a", "x")'], 'E1030: Using a String as a Number: "$a"')
+  assert_fails('appendbufline(' .. bnum .. ', "$a", "x")', ['E1030: Using a String as a Number: "$a"', 'E1030:'])
   CheckDefAndScriptFailure(['appendbufline(1, 1, {"a": 10})'], ['E1013: Argument 3: type mismatch, expected string but got dict<number>', 'E1224: String, Number or List required for argument 3'])
   bnum->bufwinid()->win_gotoid()
   appendbufline('', 0, 'numbers')
@@ -768,6 +771,10 @@
   setline(1, ['one', 'two'])
   deletebufline('', 1)
   getline(1, '$')->assert_equal(['two'])
+
+  assert_fails('deletebufline("", "$a", "$b")', ['E1030: Using a String as a Number: "$a"', 'E1030: Using a String as a Number: "$a"'])
+  assert_fails('deletebufline("", "$", "$b")', ['E1030: Using a String as a Number: "$b"', 'E1030: Using a String as a Number: "$b"'])
+
   bwipe!
 enddef
 
@@ -1459,7 +1466,10 @@
   getbufline(-1, '$', '$')->assert_equal([])
   getbufline(-1, 1, '$')->assert_equal([])
 
+  assert_fails('getbufline("", "$a", "$b")', ['E1030: Using a String as a Number: "$a"', 'E1030: Using a String as a Number: "$a"'])
+  assert_fails('getbufline("", "$", "$b")', ['E1030: Using a String as a Number: "$b"', 'E1030: Using a String as a Number: "$b"'])
   bwipe!
+
   CheckDefAndScriptFailure(['getbufline([], 2)'], ['E1013: Argument 1: type mismatch, expected string but got list<unknown>', 'E1220: String or Number required for argument 1'])
   CheckDefAndScriptFailure(['getbufline("a", [])'], ['E1013: Argument 2: type mismatch, expected string but got list<unknown>', 'E1220: String or Number required for argument 2'])
   CheckDefAndScriptFailure(['getbufline("a", 2, 0z10)'], ['E1013: Argument 3: type mismatch, expected string but got blob', 'E1220: String or Number required for argument 3'])
@@ -3311,6 +3321,7 @@
   CheckDefAndScriptFailure(['setline([1], "x")'], ['E1013: Argument 1: type mismatch, expected string but got list<number>', 'E1220: String or Number required for argument 1'])
   CheckDefExecAndScriptFailure(['setline("", "x")'], 'E1209: Invalid value for a line number')
   CheckDefExecAndScriptFailure(['setline(-1, "x")'], 'E966: Invalid line number: -1')
+  assert_fails('setline(".a", "x")', ['E1209:', 'E1209:'])
   bw!
 enddef
 
diff --git a/src/typval.c b/src/typval.c
index 2f773b6..34ff47c 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -2249,9 +2249,10 @@
     if (lnum <= 0 && argvars[0].v_type != VAR_NUMBER)
     {
 	int	fnum;
-	pos_T	*fp = var2fpos(&argvars[0], TRUE, &fnum, FALSE);
+	pos_T	*fp;
 
 	// no valid number, try using arg like line()
+	fp = var2fpos(&argvars[0], TRUE, &fnum, FALSE);
 	if (fp != NULL)
 	    lnum = fp->lnum;
     }
@@ -2269,6 +2270,7 @@
     if (argvars[0].v_type == VAR_STRING
 	    && argvars[0].vval.v_string != NULL
 	    && argvars[0].vval.v_string[0] == '$'
+	    && argvars[0].vval.v_string[1] == NUL
 	    && buf != NULL)
 	return buf->b_ml.ml_line_count;
     return (linenr_T)tv_get_number_chk(&argvars[0], NULL);
diff --git a/src/version.c b/src/version.c
index 4e6c07b..2045de9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3919,
+/**/
     3918,
 /**/
     3917,