Better error messages during compilation and fix for wide return types

lib/duby/ast/flow.rb

@@ -81,7 +81,7 @@ def infer(typer)
                   @inferred_type = then_type.narrow(else_type)
                   resolved! if condition_type
                 else
-                  raise Typer::InferenceError.new("if statement with incompatible result types")
+                  raise Typer::InferenceError.new("if statement with incompatible result types #{then_type} and #{else_type}")
                 end
               end
             else

lib/duby/jvm/base.rb

@@ -15,7 +15,12 @@ def initialize(filename)
       end
 
       def compile(ast, expression = false)
-        ast.compile(self, expression)
+        begin
+          ast.compile(self, expression)
+        rescue => ex
+          Duby.print_error(ex.message, ast.position)
+          raise ex
+        end
         log "Compilation successful!"
       end
 

lib/duby/jvm/types/methods.rb

@@ -19,7 +19,7 @@ def convert_args(compiler, values, types=nil)
       # TODO varargs
       types ||= argument_types
       values.zip(types).each do |value, type|
-        value.compile(compiler, true)
+        compiler.compile(value, true)
         if type.primitive? && type != value.inferred_type
             value.inferred_type.widen(compiler.method, type)
         end
@@ -208,7 +208,11 @@ def call(compiler, ast, expression)
       end
 
       unless expression || void?
-        compiler.method.pop
+        if return_type.wide?
+          compiler.method.pop2
+        else
+          compiler.method.pop
+        end
       end
     end