fix: add NaN-safe header parsing and remove non-null assertions

- Add parseHeaderInt helper with parseInt and NaN validation
- Replace non-null assertions with optional chaining in tests
- Add tests for invalid header values (NaN handling)

Author: jeffredodd

src/hooks/usePagination/usePagination.test.ts

@@ -33,6 +33,24 @@ describe('extractPaginationMeta', () => {
     const result = extractPaginationMeta(httpMeta)
     expect(result.totalItems).toBe(0)
   })
+
+  test('defaults totalPages to 1 when header is invalid', () => {
+    const httpMeta = createMockHttpMeta({ 'x-total-pages': 'invalid' })
+    const result = extractPaginationMeta(httpMeta)
+    expect(result.totalPages).toBe(1)
+  })
+
+  test('defaults totalItems to 0 when header is invalid', () => {
+    const httpMeta = createMockHttpMeta({ 'x-total-count': 'abc' })
+    const result = extractPaginationMeta(httpMeta)
+    expect(result.totalItems).toBe(0)
+  })
+
+  test('defaults totalPages to 1 when header is empty string', () => {
+    const httpMeta = createMockHttpMeta({ 'x-total-pages': '' })
+    const result = extractPaginationMeta(httpMeta)
+    expect(result.totalPages).toBe(1)
+  })
 })
 
 describe('usePagination', () => {
@@ -96,10 +114,9 @@ describe('usePagination', () => {
       })
 
       expect(setCurrentPage).toHaveBeenCalled()
-      const call = setCurrentPage.mock.calls[0]
-      expect(call).toBeDefined()
-      const updateFn = call![0] as (prev: number) => number
-      expect(updateFn(3)).toBe(2)
+      const updateFn = setCurrentPage.mock.calls[0]?.[0] as ((prev: number) => number) | undefined
+      expect(updateFn).toBeDefined()
+      expect(updateFn?.(3)).toBe(2)
     })
 
     test('handleNextPage increments page', () => {
@@ -114,10 +131,9 @@ describe('usePagination', () => {
       })
 
       expect(setCurrentPage).toHaveBeenCalled()
-      const call = setCurrentPage.mock.calls[0]
-      expect(call).toBeDefined()
-      const updateFn = call![0] as (prev: number) => number
-      expect(updateFn(3)).toBe(4)
+      const updateFn = setCurrentPage.mock.calls[0]?.[0] as ((prev: number) => number) | undefined
+      expect(updateFn).toBeDefined()
+      expect(updateFn?.(3)).toBe(4)
     })
 
     test('handleLastPage sets page to totalPages', () => {
@@ -163,10 +179,9 @@ describe('usePagination', () => {
         result.current.handlePreviousPage()
       })
 
-      const call = setCurrentPage.mock.calls[0]
-      expect(call).toBeDefined()
-      const updateFn = call![0] as (prev: number) => number
-      expect(updateFn(1)).toBe(1)
+      const updateFn = setCurrentPage.mock.calls[0]?.[0] as ((prev: number) => number) | undefined
+      expect(updateFn).toBeDefined()
+      expect(updateFn?.(1)).toBe(1)
     })
 
     test('handleNextPage on last page stays on last page', () => {
@@ -180,10 +195,9 @@ describe('usePagination', () => {
         result.current.handleNextPage()
       })
 
-      const call = setCurrentPage.mock.calls[0]
-      expect(call).toBeDefined()
-      const updateFn = call![0] as (prev: number) => number
-      expect(updateFn(5)).toBe(5)
+      const updateFn = setCurrentPage.mock.calls[0]?.[0] as ((prev: number) => number) | undefined
+      expect(updateFn).toBeDefined()
+      expect(updateFn?.(5)).toBe(5)
     })
   })
 

src/hooks/usePagination/usePagination.ts

@@ -12,10 +12,16 @@ type PaginationState = {
   setItemsPerPage: React.Dispatch<React.SetStateAction<PaginationItemsPerPage>>
 }
 
+function parseHeaderInt(value: string | null, defaultValue: number): number {
+  if (value === null) return defaultValue
+  const parsed = parseInt(value, 10)
+  return Number.isNaN(parsed) ? defaultValue : parsed
+}
+
 export function extractPaginationMeta(httpMeta?: HttpMeta | null) {
   return {
-    totalPages: Number(httpMeta?.response.headers.get('x-total-pages') ?? 1),
-    totalItems: Number(httpMeta?.response.headers.get('x-total-count') ?? 0),
+    totalPages: parseHeaderInt(httpMeta?.response.headers.get('x-total-pages') ?? null, 1),
+    totalItems: parseHeaderInt(httpMeta?.response.headers.get('x-total-count') ?? null, 0),
   }
 }