support arithmetic operators for both reals and integers

should be simplified but fixes tests for now

src/main/java/de/tla2b/analysis/TypeChecker.java

@@ -1193,25 +1193,44 @@ public class TypeChecker extends BuiltInOPs implements ASTConstants, BBuildIns,
 		case B_OPCODE_div: // /
 		case B_OPCODE_mod: // % modulo
 		case B_OPCODE_exp: { // x hoch y, x^y
+			TLAType type;
+			// TODO: Simplify
+			if (expected instanceof RealType) {
 				try {
 					RealType.getInstance().unify(expected);
-				for (int i = 0; i < n.getArgs().length; i++) {
-					visitExprOrOpArgNode(n.getArgs()[i], RealType.getInstance());
-				}
-				return RealType.getInstance();
+					type = RealType.getInstance();
 				} catch (UnificationException e) {
+					throw new TypeErrorException(String.format("Expected %s, found REAL at '%s',%n%s", expected,
+							n.getOperator().getName(), n.getLocation()));
+				}
+			} else if (expected instanceof IntType) {
 				try {
 					IntType.getInstance().unify(expected);
+					type = IntType.getInstance();
+				} catch (UnificationException ue) {
+					throw new TypeErrorException(String.format("Expected %s, found INTEGER at '%s',%n%s", expected,
+						n.getOperator().getName(), n.getLocation()));
+				}
+			} else if (expected instanceof UntypedType) {
+				IntType.getInstance().unify(expected);
+				type = IntType.getInstance();
+				try {
 					for (int i = 0; i < n.getArgs().length; i++) {
-						visitExprOrOpArgNode(n.getArgs()[i], IntType.getInstance());
+						visitExprOrOpArgNode(n.getArgs()[i], type);
 					}
-					return IntType.getInstance();
-				} catch (UnificationException e2) {
+				} catch (TypeErrorException e) {
+					RealType.getInstance().unify(expected);
+					type = RealType.getInstance();
+				}
+			} else {
 				throw new TypeErrorException(String.format("Expected %s, found INTEGER at '%s',%n%s", expected,
 					n.getOperator().getName(), n.getLocation()));
 			}
+			for (int i = 0; i < n.getArgs().length; i++) {
+				visitExprOrOpArgNode(n.getArgs()[i], type);
 			}
 
+			return type;
 		}
 
 		case B_OPCODE_dotdot: // ..