patch 8.2.2857: Vim9: exception in ISN_INSTR caught at wrong level

Problem:    Vim9: exception in ISN_INSTR caught at wrong level.
Solution:   Set the starting trylevel in exec_instructions(). (closes #8214)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 39c36df..9aa93de 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3131,7 +3131,8 @@
     s = skipwhite(s);
     trailing_error = *s != NUL;
 
-    if (expr_res == FAIL || trailing_error)
+    if (expr_res == FAIL || trailing_error
+				       || ga_grow(&cctx->ctx_instr, 1) == FAIL)
     {
 	if (trailing_error)
 	    semsg(_(e_trailing_arg), s);
@@ -3185,7 +3186,7 @@
 	    return FAIL;
 	++*argcount;
 
-	if (is_searchpair && *argcount == 5
+	if (is_searchpair && *argcount >= 5
 		&& cctx->ctx_instr.ga_len == instr_count + 1)
 	{
 	    isn_T *isn = ((isn_T *)cctx->ctx_instr.ga_data) + instr_count;