checker: improve mismatched range types error messages

vlib/v/checker/match.v

@@ -162,7 +162,8 @@ fn (mut c Checker) match_exprs(mut node ast.MatchExpr, cond_type_sym ast.TypeSym
 							c.error('start value is higher than end value', branch.pos)
 						}
 					} else {
-						c.error('mismatched range types', low_expr.pos)
+						c.error('mismatched range types - $expr.low is an integer, but $expr.high is not',
+							low_expr.pos)
 					}
 				} else if low_expr is ast.CharLiteral {
 					if high_expr is ast.CharLiteral && final_cond_sym.kind in [.u8, .char, .rune] {
@@ -172,7 +173,9 @@ fn (mut c Checker) match_exprs(mut node ast.MatchExpr, cond_type_sym ast.TypeSym
 							c.error('start value is higher than end value', branch.pos)
 						}
 					} else {
-						c.error('mismatched range types', low_expr.pos)
+						typ := c.table.type_to_str(c.expr(node.cond))
+						c.error('mismatched range types - trying to match `$node.cond`, which has type `$typ`, to a range of `rune`',
+							low_expr.pos)
 					}
 				} else {
 					typ := c.table.type_to_str(c.expr(expr.low))

vlib/v/checker/tests/match_range_mismatch_type_err.out

@@ -1,7 +1,14 @@
-vlib/v/checker/tests/match_range_mismatch_type_err.vv:4:3: error: mismatched range types
+vlib/v/checker/tests/match_range_mismatch_type_err.vv:4:3: error: mismatched range types - trying to match `x`, which has type `string`, to a range of `rune`
     2 |     x := '1'
     3 |     match x {
     4 |         `0`...`9` {
       |         ~~~
     5 |             println('0-9')
     6 |         }
+vlib/v/checker/tests/match_range_mismatch_type_err.vv:16:3: error: mismatched range types - 0 is an integer, but `9` is not
+   14 |     x := 1
+   15 |     match x {
+   16 |         0...`9` {}
+      |         ^
+   17 |         else {}
+   18 |     }

vlib/v/checker/tests/match_range_mismatch_type_err.vv

@@ -9,3 +9,11 @@ fn main() {
 		}
 	}
 }
+
+fn abc() {
+	x := 1
+	match x {
+		0...`9` {}
+		else {}
+	}
+}