useRowSelect: remove redundant checks (#1918)

* useRowSelect: remove redundant checks

* Update useRowSelect.js

Co-authored-by: Tanner Linsley <tannerlinsley@gmail.com>

.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/index.js": {
-    "bundled": 130976,
-    "minified": 61378,
-    "gzipped": 15745
+    "bundled": 130947,
+    "minified": 61370,
+    "gzipped": 15740
   },
   "dist/index.es.js": {
-    "bundled": 130034,
-    "minified": 60537,
-    "gzipped": 15571,
+    "bundled": 130005,
+    "minified": 60529,
+    "gzipped": 15565,
     "treeshaked": {
       "rollup": {
         "code": 80,

src/plugin-hooks/useRowSelect.js

@@ -136,9 +136,9 @@ function reducer(state, action, previousState, instance) {
       const row = rowsById[id]
 
       if (!row.isGrouped) {
-        if (!isSelected && shouldExist) {
+        if (shouldExist) {
           newSelectedRowIds[id] = true
-        } else if (isSelected && !shouldExist) {
+        } else {
           delete newSelectedRowIds[id]
         }
       }