fix: math filters coerce invalid string to 0, #813 (#819)

src/util/limiter.ts

@@ -1,5 +1,4 @@
 import { assert } from './assert'
-import { toNumber } from './underscore'
 
 export class Limiter {
   private message: string
@@ -10,12 +9,12 @@ export class Limiter {
     this.limit = limit
   }
   use (count: number) {
-    count = toNumber(count)
+    count = +count || 0
     assert(this.base + count <= this.limit, this.message)
     this.base += count
   }
   check (count: number) {
-    count = toNumber(count)
+    count = +count || 0
     assert(count <= this.limit, this.message)
   }
 }

src/util/underscore.ts

@@ -67,8 +67,7 @@ export function toValue (value: any): any {
 }
 
 export function toNumber (value: any): number {
-  value = Number(value)
-  return isNaN(value) ? 0 : value
+  return +toValue(value) || 0
 }
 
 export function isNumber (value: any): value is number {
@@ -191,6 +190,10 @@ export function argumentsToValue<F extends (...args: any) => any, T> (fn: F) {
   return function (this: T, ...args: Parameters<F>) { return fn.call(this, ...args.map(toValue)) }
 }
 
+export function argumentsToNumber<F extends (...args: any) => any, T> (fn: F) {
+  return function (this: T, ...args: Parameters<F>) { return fn.call(this, ...args.map(toNumber)) }
+}
+
 export function escapeRegExp (text: string) {
   return text.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&')
 }