Support of TS 4.1 with noUncheckedIndexedAccess

[ondrejvelisek]

Hi there,

I have similar problem as #37
TS 4.1 introduced new compilerOption noUncheckedIndexedAccess. see:
https://www.typescriptlang.org/tsconfig#noUncheckedIndexedAccess

When I use TS 4.1 or above with this option, micro-memoize fails to compile.

To reproduce bug, create a project with TS 4.1 or above, turn on noUncheckedIndexedAccess, import and use micro-memoize and run a TS build. I see:

tsc --noEmit

node_modules/micro-memoize/src/Cache.ts:82:23 - error TS2345: Argument of type 'Key | undefined' is not assignable to parameter of type 'Key'.
  Type 'undefined' is not assignable to type 'any[]'.

82     if (isMatchingKey(keys[0], keyToMatch)) {
                         ~~~~~~~

node_modules/micro-memoize/src/Cache.ts:88:27 - error TS2345: Argument of type 'Key | undefined' is not assignable to parameter of type 'Key'.
  Type 'undefined' is not assignable to type 'any[]'.

88         if (isMatchingKey(keys[index], keyToMatch)) {
                             ~~~~~~~~~~~

node_modules/micro-memoize/src/Cache.ts:176:13 - error TS2339: Property 'length' does not exist on type 'Key | undefined'.

176     const { length } = existingKey;
                ~~~~~~

node_modules/micro-memoize/src/Cache.ts:186:22 - error TS2532: Object is possibly 'undefined'.

186         if (!isEqual(existingKey[index], keyToMatch[index])) {
                         ~~~~~~~~~~~

node_modules/micro-memoize/src/Cache.ts:194:20 - error TS2532: Object is possibly 'undefined'.

194     return isEqual(existingKey[0], keyToMatch[0]) ? 0 : -1;
                       ~~~~~~~~~~~

node_modules/micro-memoize/src/Cache.ts:220:7 - error TS2322: Type 'Key | undefined' is not assignable to type 'Key'.
  Type 'undefined' is not assignable to type 'any[]'.

220       keys[index + 1] = keys[index];
          ~~~~~~~~~~~~~~~

node_modules/micro-memoize/src/Cache.ts:269:43 - error TS2345: Argument of type 'Key | undefined' is not assignable to parameter of type 'RawKey'.
  Type 'undefined' is not assignable to type 'RawKey'.

269         const keyIndex = this.getKeyIndex(firstKey);
                                              ~~~~~~~~


Found 7 errors in the same file, starting at: node_modules/micro-memoize/src/Cache.ts:82

[planttheidea]

This should be fixed as-of 4.0.10. If you have any more issues, please let me know!