Added customized Pane type errors

panel/pane/base.py

@@ -69,14 +69,17 @@ class PaneBase(Reactive):
     def __init__(self, object=None, **params):
         applies = self.applies(object)
         if (isinstance(applies, bool) and not applies) and object is not None :
-            raise ValueError("%s pane does not support objects of type '%s'" %
-                             (type(self).__name__, type(object).__name__))
-
+            self._type_error(object)
+
         super(PaneBase, self).__init__(object=object, **params)
         kwargs = {k: v for k, v in params.items() if k in Layoutable.param}
         self.layout = self.default_layout(self, **kwargs)
         self.param.watch(self._update_pane, self._rerender_params)
 
+    def _type_error(self, object):
+        raise ValueError("%s pane does not support objects of type '%s'." %
+                         (type(self).__name__, type(object).__name__))
+
     def __repr__(self, depth=0):
         cls = type(self).__name__
         params = param_reprs(self, ['object'])

panel/pane/image.py

@@ -60,6 +60,12 @@ def _is_url(cls, obj):
             ) and lower_string.endswith('.'+cls.imgtype)
         return False
 
+    def _type_error(self, object):
+        if isinstance(object, string_types):
+            raise ValueError("%s pane cannot parse string that is not a filename "
+                             "or URL." % type(self).__name__)
+        super(ImageBase, self)._type_error(object)
+
     def _img(self):
         if hasattr(self.object, '_repr_{}_'.format(self.imgtype)):
             return getattr(self.object, '_repr_' + self.imgtype + '_')()
@@ -175,6 +181,12 @@ def applies(cls, obj):
         return (super(SVG, cls).applies(obj) or
                 (isinstance(obj, string_types) and obj.lstrip().startswith('<svg')))
 
+    def _type_error(self, object):
+        if isinstance(object, string_types):
+            raise ValueError("%s pane cannot parse string that is not a filename, "
+                             "URL or a SVG XML contents." % type(self).__name__)
+        super(SVG, self)._type_error(object)
+
     def _img(self):
         if (isinstance(self.object, string_types) and
             self.object.lstrip().startswith('<svg')):