patch 8.2.4103: Vim9: variable declared in for loop not initialzed

Problem:    Vim9: variable declared in for loop not initialzed.
Solution:   Always initialze the variable. (closes #9535)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index afc7885..89520f9 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2256,12 +2256,17 @@
 		    case VAR_VOID:
 		    case VAR_INSTR:
 		    case VAR_SPECIAL:  // cannot happen
-			// This is skipped for local variables, they are
-			// always initialized to zero.
-			if (lhs.lhs_dest == dest_local)
+			// This is skipped for local variables, they are always
+			// initialized to zero.  But in a "for" or "while" loop
+			// the value may have been changed.
+			if (lhs.lhs_dest == dest_local
+						   && !inside_loop_scope(cctx))
 			    skip_store = TRUE;
 			else
+			{
+			    instr_count = instr->ga_len;
 			    generate_PUSHNR(cctx, 0);
+			}
 			break;
 		}
 	    }