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fix: guard against undefined client in useFeatureFlagEnabled #2655

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Merged
merged 4 commits into from
Dec 2, 2025
Merged

fix: guard against undefined client in useFeatureFlagEnabled #2655

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262c2ec
guard against undefined client
ordehi Nov 27, 2025
5ec5484
changeset
ordehi Nov 27, 2025
4ea57e7
Update .changeset/puny-rules-hide.md
ordehi Nov 27, 2025
85818a6
add guard to other hooks
ordehi Nov 27, 2025
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5 changes: 5 additions & 0 deletions .changeset/puny-rules-hide.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@posthog/react': patch
---

Updated feature flag hooks to properly check if client is initialized and prevent client is undefined errors
2 changes: 1 addition & 1 deletion packages/react/src/hooks/useActiveFeatureFlags.ts
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Expand Up @@ -13,7 +13,7 @@ export function useActiveFeatureFlags(): string[] {
}, [client])

// if the client is not loaded yet and we have a bootstrapped value, use it
if (!client.featureFlags.hasLoadedFlags && bootstrap?.featureFlags) {
if (!client?.featureFlags?.hasLoadedFlags && bootstrap?.featureFlags) {
return Object.keys(bootstrap.featureFlags)
}

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2 changes: 1 addition & 1 deletion packages/react/src/hooks/useFeatureFlagEnabled.ts
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Expand Up @@ -16,7 +16,7 @@ export function useFeatureFlagEnabled(flag: string): boolean | undefined {
const bootstrapped = bootstrap?.featureFlags?.[flag]

// if the client is not loaded yet, check if we have a bootstrapped value and then true/false it
if (!client.featureFlags.hasLoadedFlags && bootstrap?.featureFlags) {
if (!client?.featureFlags?.hasLoadedFlags && bootstrap?.featureFlags) {
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@greptile-apps greptile-apps bot Nov 27, 2025

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style: Other similar hooks (useFeatureFlagVariantKey.ts:17, useFeatureFlagPayload.ts:17, useActiveFeatureFlags.ts:16) don't use optional chaining but this one does - consider whether this change is actually needed or if the issue is elsewhere

Prompt To Fix With AI 
This is a comment left during a code review.
Path: packages/react/src/hooks/useFeatureFlagEnabled.ts
Line: 19:19

Comment:
**style:** Other similar hooks (`useFeatureFlagVariantKey.ts:17`, `useFeatureFlagPayload.ts:17`, `useActiveFeatureFlags.ts:16`) don't use optional chaining but this one does - consider whether this change is actually needed or if the issue is elsewhere

How can I resolve this? If you propose a fix, please make it concise.

return isUndefined(bootstrapped) ? undefined : !!bootstrapped
}

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2 changes: 1 addition & 1 deletion packages/react/src/hooks/useFeatureFlagPayload.ts
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Expand Up @@ -14,7 +14,7 @@ export function useFeatureFlagPayload(flag: string): JsonType {
}, [client, flag])

// if the client is not loaded yet, use the bootstrapped value
if (!client.featureFlags.hasLoadedFlags && bootstrap?.featureFlagPayloads) {
if (!client?.featureFlags?.hasLoadedFlags && bootstrap?.featureFlagPayloads) {
return bootstrap.featureFlagPayloads[flag]
}

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2 changes: 1 addition & 1 deletion packages/react/src/hooks/useFeatureFlagVariantKey.ts
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Expand Up @@ -14,7 +14,7 @@ export function useFeatureFlagVariantKey(flag: string): string | boolean | undef
})
}, [client, flag])

if (!client.featureFlags.hasLoadedFlags && bootstrap?.featureFlags) {
if (!client?.featureFlags?.hasLoadedFlags && bootstrap?.featureFlags) {
return bootstrap.featureFlags[flag]
}

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