Merge pull request #855 from kachick/segfault-kernel-catch

Guard Kernel.#catch without block from segfault

spec/tags/core/kernel/catch_tags.txt

@@ -3,7 +3,6 @@ fails:Kernel.catch raises an ArgumentError if a Symbol is thrown for a String ca
 fails:Kernel.catch raises an ArgumentError if a String with different identity is thrown
 fails:Kernel.catch accepts an object as an argument
 fails:Kernel.catch yields an object when called without arguments
-fails:Kernel.catch raises LocalJumpError if no block is given
 fails:Kernel.catch when nested catches across invocation boundaries
 fails:Kernel.catch when nested catches in the nested invocation with the same key object
 fails:Kernel#catch is a private method

topaz/modules/kernel.py

@@ -435,6 +435,8 @@ def method_throw(self, space, name, w_value=None):
 
     @moduledef.method("catch", name="symbol")
     def method_catch(self, space, name, block):
+        if block is None:
+            raise space.error(space.w_LocalJumpError, "no block given")
         from topaz.interpreter import Throw
         with space.getexecutioncontext().catch_block(name):
             try: