Fix bugs

Author: mdbrnowski

tests/semantic/input_compound_assignments.txt

@@ -1,5 +1,5 @@
 a = 1;
-b = 2;
+b = 2.0;
 c = eye(5);
 
 a -= 1;

utils/types.py

@@ -75,7 +75,7 @@ def __mul__(self, other):
         if isinstance(other, Int):
             if self.value is not None and other.value is not None:
                 return Int(self.value * other.value)
-            return Int(self.value * other.value)
+            return Int()
         raise TypeError()
 
     def __truediv__(self, other):