make unassigned return a hint instead of an error

ast/ast.ts

@@ -130,6 +130,7 @@ module TDev.AST {
         private stableName: string;
         private stableVersions : string[];
         public tutorialWarning: string;
+        public _hint:string;
 
         constructor() {
             super()
@@ -147,6 +148,25 @@ module TDev.AST {
             else
                 return this._error;
         }
+        public getHint()
+        {
+            var r:string = null
+            if (this.calcNode())
+                r = this.calcNode().hint
+            if (!r) return this._hint
+            if (this._hint) return r + "\n" + this._hint
+            return null
+        }
+        public addHint(msg:string)
+        {
+            if (!this._hint) this._hint = msg
+            else this._hint += "\n" + msg
+        }
+        public clearError()
+        {
+            this._error = null
+            this._hint = null
+        }
 
         public debuggerRenderContext: {
             isOnStackTrace ?: boolean;

ast/render.ts

@@ -479,12 +479,11 @@ module TDev
             }
 
             if (res == "" && node instanceof AST.Stmt) {
-                var calcNode = (<AST.Stmt>node).calcNode();
-                if (calcNode && calcNode.hint) {
-                    calcNode.hint.split("\n").forEach(h => {
+                var hint = (<AST.Stmt>node).getHint()
+                if (hint)
+                    hint.split("\n").forEach(h => {
                         res += this.message("hintMessage", Util.htmlEscape("\u270e " + h))
                     })
-                }
             }
 
             if (node.annotations)

ast/typeChecker.ts

@@ -1049,13 +1049,14 @@ module TDev.AST
                 this.updateStmtUsage(expr, "var");
         }
 
-        private checkAssignment(node:AstNode, vars:LocalDef[])
+        private checkAssignment(node:Stmt, vars:LocalDef[])
         {
             var unassigned = vars.filter((v) => this.writtenLocals.indexOf(v) < 0);
             if (unassigned.length > 0) {
-                this.setNodeError(node,
-                    lf("TD127: output parameter{0:s} {1} need to be assigned to before the action finishes",
-                             unassigned.length, unassigned.map((v) => "'" + v.getName() + "'").join(", ")))
+                node.addHint(
+                    lf("parameter{0:s} {1} may be unassigned before the action finishes",
+                             unassigned.length, 
+                             unassigned.map((v) => "'" + v.getName() + "'").join(", ")))
             }
         }