generated docs: log trace instead of error

When the error occurred for getValueText it could potentially omit
useful documentation since the page stops rendering.

lib/std/special/docs/main.js

@@ -543,7 +543,7 @@
                     return value + "";
                 }
             default:
-                throw new Error("TODO implement getValueText for this type");
+                console.trace("TODO implement getValueText for this type:", zigAnalysis.typeKinds[typeObj.kind]);
         }
     }