[FIX] parser: make t-on stricter

Before this commit, the `t-on` directive assumed that the next character
would be a -, and ignored it, so if someone would write `t-onclick` by
mistake, Owl would then add an event handler on the `lick` event,
instead of `click`.

With this commit, we improve the parser to make it stricter and fail if
there is no dash.

closes #1441

src/compiler/parser.ts

@@ -336,10 +336,10 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
 
   for (let attr of nodeAttrsNames) {
     const value = node.getAttribute(attr)!;
-    if (attr.startsWith("t-on")) {
-      if (attr === "t-on") {
-        throw new OwlError("Missing event name with t-on directive");
-      }
+    if (attr === "t-on" || attr === "t-on-") {
+      throw new OwlError("Missing event name with t-on directive");
+    }
+    if (attr.startsWith("t-on-")) {
       on = on || {};
       on[attr.slice(5)] = value;
     } else if (attr.startsWith("t-model")) {