Add error messages when external library loading fails.

source/engine/import/importer3dm.js

@@ -50,6 +50,7 @@ export class Importer3dm extends ImporterBase
                     onFinish ();
                 });
             }).catch (() => {
+                this.SetError ('Failed to load rhino3dm.');
                 onFinish ();
             });
         } else {

source/engine/import/importergltf.js

@@ -285,7 +285,7 @@ class GltfExtensions
                     callbacks.onSuccess ();
                 });
             }).catch (() => {
-                callbacks.onError ();
+                callbacks.onError ('Failed to load draco decoder.');
             });
         } else {
             callbacks.onSuccess ();
@@ -616,8 +616,8 @@ export class ImporterGltf extends ImporterBase
                 this.ImportModel (gltf);
                 onFinish ();
             },
-            onError : () => {
+            onError : (message) => {
-                this.SetError ('Failed to load draco decoder.');
+                this.SetError (message);
                 onFinish ();
             }
         });

source/engine/import/importerifc.js

@@ -51,6 +51,7 @@ export class ImporterIfc extends ImporterBase
                     onFinish ();
                 });
             }).catch (() => {
+                this.SetError ('Failed to load web-ifc.');
                 onFinish ();
             });
 		} else {

source/engine/import/importerthree.js

@@ -74,6 +74,7 @@ export class ImporterThreeBase extends ImporterBase
         LoadLibraries (libraries, () => {
             this.LoadModel (fileContent, onFinish);
         }, () => {
+            this.SetError ('Failed to load three.js loader.');
             onFinish ();
         });
     }