diff --git a/src/calibre/utils/rapydscript.py b/src/calibre/utils/rapydscript.py
index 3ae4ae7d1a..9958095f40 100644
--- a/src/calibre/utils/rapydscript.py
+++ b/src/calibre/utils/rapydscript.py
@@ -10,7 +10,7 @@ import os, json, sys, re, atexit, errno
 from threading import local
 from functools import partial
 from threading import Thread
-from Queue import Queue
+from Queue import Queue, Empty
 
 from duktape import Context, JSError, to_python
 from calibre.constants import cache_dir
@@ -223,6 +223,14 @@ class Repl(Thread):
             'lib_path': self.libdir or os.path.dirname(P(COMPILER_PATH))  # TODO: Change this to load pyj files from the src code
         }
 
+    def get_from_repl(self):
+        while True:
+            try:
+                return self.from_repl.get(True, 1)
+            except Empty:
+                if not self.is_alive():
+                    raise SystemExit(1)
+
     def run(self):
         self.init_ctx()
         rl = None
@@ -252,6 +260,8 @@ class Repl(Thread):
         ''')
         rl = self.ctx.g.rl
         self.ctx.eval('module.exports(repl_options)')
+        completer = to_python(rl.completer)
+
         while True:
             ev, line = self.to_repl.get()
             try:
@@ -261,12 +271,11 @@ class Repl(Thread):
                 elif ev == 'line':
                     rl.send_line(line)
                 else:
-                    val = rl.completer(line)
+                    val = completer(line)
                     val = to_python(val)
                     self.from_repl.put(val[0])
             except Exception as e:
-                if 'JSError' in e.__class__.__name__:
-                    e = JSError(e)  # A bare JSError
+                if isinstance(e, JSError):
                     print (e.stack or e.message, file=sys.stderr)
                 else:
                     import traceback
@@ -290,7 +299,7 @@ class Repl(Thread):
         def completer(text, num):
             if self.completions is None:
                 self.to_repl.put(('complete', text))
-                self.completions = self.from_repl.get()
+                self.completions = filter(None, self.get_from_repl())
                 if self.completions is None:
                     return None
             try:
@@ -302,7 +311,7 @@ class Repl(Thread):
             self.readline.set_completer(completer)
 
         while True:
-            lw = self.from_repl.get()
+            lw = self.get_from_repl()
             if lw is None:
                 raise SystemExit(1)
             q = self.prompt
diff --git a/src/duktape/__init__.py b/src/duktape/__init__.py
index a88e69eaf5..91d7a6aee3 100644
--- a/src/duktape/__init__.py
+++ b/src/duktape/__init__.py
@@ -24,7 +24,22 @@ exports.readFileSync = Duktape.readfile;
 '''
 vm = '''
 exports.createContext = Duktape.create_context;
-exports.runInContext = Duktape.run_in_context;
+exports.runInContext = function(code, ctx) {
+    var result = Duktape.run_in_context(code, ctx);
+    if (result[0]) return result[1];
+    var cls = Error;
+    var e = result[1];
+    if (e.name) {
+        try {
+            cls = eval(e.name);
+        } catch(e) {}
+    }
+    var err = cls(e.message);
+    err.fileName = e.fileName;
+    err.lineNumber = e.lineNumber;
+    err.stack = e.stack;
+    throw err;
+};
 '''
 path = '''
 exports.join = function () { return arguments[0] + '/' + arguments[1]; }
@@ -74,7 +89,13 @@ class Function(object):
         return str('[Function: %s(...) from file: %s]' % (x.name, x.fileName))
 
     def __call__(self, *args, **kwargs):
-        return self.func(*args, **kwargs)
+        try:
+            return self.func(*args, **kwargs)
+        except dukpy.JSError as e:
+            self.reraise(e)
+
+    def reraise(self, e):
+        raise JSError(e), None, sys.exc_info()[2]
 
 def to_python(x):
     try:
@@ -113,6 +134,15 @@ class JSError(Exception):
             Exception.__init__(self, type('')(e))
             self.name = self.js_message = self.fileName = self.lineNumber = self.stack = None
 
+    def as_dict(self):
+        return {
+            'name':self.name or undefined,
+            'message': self.js_message or self.message,
+            'fileName': self.fileName or undefined,
+            'lineNumber': self.lineNumber or undefined,
+            'stack': self.stack or undefined
+        }
+
 contexts = {}
 
 def create_context(base_dirs, *args):
@@ -125,8 +155,12 @@ def create_context(base_dirs, *args):
     return key
 
 def run_in_context(code, ctx, options=None):
-    ans = contexts[ctx].eval(code)
-    return to_python(ans)
+    c = contexts[ctx]
+    try:
+        ans = c.eval(code)
+    except JSError as e:
+        return [False, e.as_dict()]
+    return [True, to_python(ans)]
 
 class Context(object):