checker: missing mutability check for array.delete calls (#18096)

vlib/v/checker/fn.v

@@ -2535,6 +2535,7 @@ fn (mut c Checker) array_builtin_method_call(mut node ast.CallExpr, left_type as
 			node.receiver_type = left_type
 		}
 	} else if method_name == 'delete' {
+		c.fail_if_immutable(node.left)
 		unwrapped_left_sym := c.table.sym(c.unwrap_generic(left_type))
 		if method := c.table.find_method(unwrapped_left_sym, method_name) {
 			node.receiver_type = method.receiver_type

vlib/v/checker/tests/array_delete_imut_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/array_delete_imut_err.vv:5:2: error: `a` is immutable, declare it with `mut` to make it mutable
+    3 |     println(a)
+    4 | 
+    5 |     a.delete(1)
+      |     ^
+    6 |     println(a)
+    7 | }

vlib/v/checker/tests/array_delete_imut_err.vv

@@ -0,0 +1,7 @@
+fn main() {
+	a := [1, 2, 3, 4]
+	println(a)
+
+	a.delete(1)
+	println(a)
+}

vlib/v/checker/tests/array_delete_print_err.out

@@ -1,12 +1,12 @@
 vlib/v/checker/tests/array_delete_print_err.vv:3:2: error: `println` can not print void expressions
     1 | fn main() {
-    2 |     a := []string{}
+    2 |     mut a := []string{}
     3 |     println(a.delete(0))
       |     ~~~~~~~~~~~~~~~~~~~~
     4 |     println('${a.delete(0)}')
     5 | }
 vlib/v/checker/tests/array_delete_print_err.vv:4:15: error: expression does not return a value
-    2 |     a := []string{}
+    2 |     mut a := []string{}
     3 |     println(a.delete(0))
     4 |     println('${a.delete(0)}')
       |                  ~~~~~~~~~

vlib/v/checker/tests/array_delete_print_err.vv

@@ -1,5 +1,5 @@
 fn main() {
-	a := []string{}
+	mut a := []string{}
 	println(a.delete(0))
 	println('${a.delete(0)}')
 }