Perf return session length return type (#8924)

Fix FPRSessionDetails copy implemention to retain the session creation time.

Author: visumickey

FirebasePerformance/CHANGELOG.md

@@ -1,4 +1,7 @@
-# Pending
+# Unreleased
+* Fix a crash related to FPRSessionDetails. (#8691)
+
+# Version 8.8.0
 * Create a random number of delay for remote config fetch during app starts.
 * Fix log spamming when Firebase Performance is disabled. (#8423, #8577)
 * Fix heap-heap-buffer overflow when decoding strings. (#8628)

FirebasePerformance/Sources/AppActivity/FPRSessionDetails.m

@@ -36,12 +36,13 @@ - (instancetype)initWithSessionId:(NSString *)sessionId options:(FPRSessionOptio
 - (FPRSessionDetails *)copyWithZone:(NSZone *)zone {
   FPRSessionDetails *detailsCopy = [[[self class] allocWithZone:zone] initWithSessionId:_sessionId
                                                                                 options:_options];
+  detailsCopy.sessionCreationTime = _sessionCreationTime;
   return detailsCopy;
 }
 
 - (NSUInteger)sessionLengthInMinutes {
   NSTimeInterval sessionLengthInSeconds = ABS([self.sessionCreationTime timeIntervalSinceNow]);
-  return (sessionLengthInSeconds / 60);
+  return (NSUInteger)(sessionLengthInSeconds / 60);
 }
 
 - (BOOL)isEqual:(FPRSessionDetails *)detailsObject {

FirebasePerformance/Tests/Unit/FPRSessionDetailsTest.m

@@ -29,6 +29,17 @@ - (void)testInstanceCreation {
   XCTAssertNotNil(details);
 }
 
+/** Validates object copy contains same details as the source. */
+- (void)testInstanceCopy {
+  FPRSessionDetails *details = [[FPRSessionDetails alloc] initWithSessionId:@"random"
+                                                                    options:FPRSessionOptionsNone];
+  FPRSessionDetails *detailsCopy = [details copy];
+  XCTAssertEqual(details.sessionId, detailsCopy.sessionId);
+  XCTAssertEqual(details.options, detailsCopy.options);
+  XCTAssertEqual(details.sessionLengthInMinutes, detailsCopy.sessionLengthInMinutes);
+  XCTAssertNotNil(details);
+}
+
 /** Validated that the details are valid. */
 - (void)testDetailsData {
   FPRSessionDetails *details = [[FPRSessionDetails alloc] initWithSessionId:@"random"