patch 8.2.0595: Vim9: not all commands using ends_excmd() tested

Problem:    Vim9: not all commands using ends_excmd() tested.
Solution:   Find # comment after regular commands. Add more tests.  Report
            error for where it was caused.
diff --git a/src/vim9compile.c b/src/vim9compile.c
index e8e8598..64f7dd5 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2434,8 +2434,10 @@
     }
 
     // If the name is a variable, load it and use PCALL.
+    // Not for g:Func(), we don't know if it is a variable or not.
     p = namebuf;
-    if (compile_load(&p, namebuf + varlen, cctx, FALSE) == OK)
+    if (STRNCMP(namebuf, "g:", 2) != 0
+	    && compile_load(&p, namebuf + varlen, cctx, FALSE) == OK)
     {
 	res = generate_PCALL(cctx, argcount, FALSE);
 	goto theend;