Fix codegen of trampoline wrappers to no-return functions

spec/compiler/codegen/fun_spec.cr

@@ -43,6 +43,21 @@ describe "Code gen: fun" do
     )).to_i.should eq(1)
   end
 
+  it "call fun pointer of instance method that raises" do
+    run(%(
+      require "prelude"
+      class Foo
+        def coco
+          raise "foo"
+        end
+      end
+
+      foo = Foo.new
+      f = ->foo.coco
+      f.call rescue 1
+    )).to_i.should eq(1)
+  end
+
   it "codegens fun with another var" do
     run("
       def foo(x)

src/compiler/crystal/codegen.cr

@@ -752,7 +752,9 @@ module Crystal
           LLVM.add_attribute func.get_param(0), LibLLVM::Attribute::Nest
           func.append_basic_block("entry") do |builder|
             call_ret = builder.call target_fun, func.params
-            if target_def.type.void?
+            if target_def.no_returns?
+              builder.unreachable
+            elsif target_def.type.void?
               builder.ret
             else
               builder.ret call_ret