parser: fix unary operators causing stack overflow

examples/hello.ry

@@ -36,11 +36,14 @@ fn func_refer_param(b: i32) i32 {
 }
 
 fn multwo(num: i32, double_flag: bool) i32 {
+    if (!double_flag) {
+        var value = false;
+        return value;
+    }
+
     if (double_flag) {
-        var truthy = true;
         return num * 2;
     } else {
-        var falsey = false;
         return num;
     }
 }

src/parsers.zig

@@ -1033,8 +1033,9 @@ pub const Parser = struct {
 
     fn parseUnary(self: *@This()) anyerror!*Expr {
         if (self.compareAnyOf(&[_]TokenType{ .Bang, .Minus })) {
-            var op = self.previous();
-            var right = try self.parseUnary();
+            var op = self.peek();
+            _ = try self.nextToken();
+            var right = try self.parseCall();
 
             return try self.mkUnary(try toUnaryOperator(op), right);
         }