Fix ESM issue with perplex by introducing a workaround

See evanw/esbuild#1719 for more info

src/lib/lexer.ts

@@ -0,0 +1,7 @@
+import  perplex from 'perplex'
+
+// Work around an issue with ESM and the perplex module. Explicitly re-export
+// the .default to make it work.
+// See https://github.com/evanw/esbuild/issues/1719
+// @ts-ignore
+export const Lexer = perplex.default

src/lib/predicateParser.ts

@@ -4,9 +4,9 @@
  *
  * See https://docs.commercetools.com/api/predicates/query
  */
-import perplex from 'perplex'
 import { ITokenPosition, Parser } from 'pratt'
 import { haversineDistance } from './haversine'
+import { Lexer } from './lexer'
 
 export class PredicateError {
   message: string
@@ -104,7 +104,7 @@ const resolveValue = (obj: any, val: TypeSymbol): any => {
 }
 
 const getLexer = (value: string) =>
-  new perplex(value)
+  new Lexer(value)
 
     .token('AND', /and(?![-_a-z0-9]+)/i)
     .token('OR', /or(?![-_a-z0-9]+)/i)

src/lib/projectionSearchFilter.ts

@@ -3,10 +3,10 @@
  */
 
 import type { ProductProjection, ProductVariant } from '@commercetools/platform-sdk'
-import perplex from 'perplex'
 import Parser from 'pratt'
 import { nestedLookup } from '../helpers'
 import type { Writable } from '../types'
+import { Lexer } from './lexer'
 
 type MatchFunc = (target: any) => boolean
 
@@ -72,7 +72,7 @@ export const parseFilterExpression = (
 }
 
 const getLexer = (value: string) =>
-  new perplex(value)
+  new Lexer(value)
     .token('MISSING', /missing(?![-_a-z0-9]+)/i)
     .token('EXISTS', /exists(?![-_a-z0-9]+)/i)
     .token('RANGE', /range(?![-_a-z0-9]+)/i)
@@ -211,7 +211,7 @@ const parseFilter = (filter: string): ExpressionSet => {
       // Return a list of functions which matches the ranges. These functions
       // are processed as an OR clause
       return ranges.map((range: any) => {
-        let func = undefined
+        let func: (obj: any) => boolean
 
         if (range.start !== null && range.stop !== null) {
           func = (obj: any): boolean => obj >= range.start && obj <= range.stop