Adjusted handling of coalesce operator so it can also return an optional if the second operand is an optional.

CodeModel/src/main/java/org/openzen/zenscript/codemodel/type/GlobalTypeRegistry.java

@@ -125,7 +125,7 @@ public class GlobalTypeRegistry {
 		}
 	}
 	
-	private OptionalTypeID getOptional(ITypeID original) {
+	public OptionalTypeID getOptional(ITypeID original) {
 		if (optionalTypes.containsKey(original)) {
 			return optionalTypes.get(original);
 		} else {

Parser/src/main/java/org/openzen/zenscript/parser/expression/ParsedExpressionCoalesce.java

@@ -9,6 +9,8 @@ import org.openzen.zenscript.codemodel.expression.CoalesceExpression;
 import org.openzen.zenscript.codemodel.expression.Expression;
 import org.openzen.zenscript.codemodel.partial.IPartialExpression;
 import org.openzen.zenscript.codemodel.type.ITypeID;
+import org.openzen.zenscript.codemodel.type.OptionalTypeID;
+import org.openzen.zenscript.codemodel.type.member.TypeMembers;
 import org.openzen.zenscript.linker.ExpressionScope;
 import org.openzen.zenscript.shared.CodePosition;
 import org.openzen.zenscript.shared.CompileException;
@@ -37,7 +39,13 @@ public class ParsedExpressionCoalesce extends ParsedExpression {
 			throw new CompileException(position, CompileExceptionCode.COALESCE_TARGET_NOT_OPTIONAL, "Type of the first expression is not optional");
 		
 		ITypeID resultType = cLeftType.getOptionalBase();
-		Expression cRight = right.compile(scope.withHint(resultType)).eval().castImplicit(position, scope, resultType);
+		Expression cRight = right.compile(scope.withHint(resultType)).eval();
+		
+		TypeMembers resultTypeMembers = scope.getTypeMembers(resultType);
+		resultType = resultTypeMembers.union(cRight.type);
+		cLeft = cLeft.castImplicit(position, scope, resultType.isOptional() ? resultType : scope.getTypeRegistry().getOptional(resultType));
+		cRight = cRight.castImplicit(position, scope, resultType);
+		
 		return new CoalesceExpression(position, cLeft, cRight);
 	}