MallocStackLogging breaks Segment when fetching user agent

[lhunath]

Describe the bug
When MallocStackLogging is enabled in an app's scheme, Segment breaks on

Self.asyncUserAgent = WKWebView().value(forKey: "userAgent") as? String

with main (1): EXC_BREAKPOINT (code=1, subcode=0x1ab7b7a18)

To Reproduce
Steps to reproduce the behavior:

1. In your application scheme, enable MallocStackLogging
2. Initialize and start up segment on launch
3. See error

Expected behavior
no crash during start-up

Screenshots

Platform (please complete the following information):

• Library Version in use: 1.5.11
• Platform being tested: iOS
• Integrations in use: Firebase

Additional context
Maybe related: #229
Backtrace:

(lldb) bt
* thread #1, name = 'main', queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x1ab7b7a18)
    frame #0: 0x00000001ab7b7a18 libsystem_malloc.dylib`xzm_malloc_zone_free_slow.cold.1 + 28
    frame #1: 0x00000001ab7b19cc libsystem_malloc.dylib`xzm_malloc_zone_free_slow + 520
    frame #2: 0x00000001b2c5f4bc JavaScriptCore`pas_try_deallocate_slow_no_cache + 428
    frame #3: 0x00000001b1780fac JavaScriptCore`WTF::String::String(__CFString const*) + 620
    frame #4: 0x00000001b09176b4 WebKit`WebKit::isFullWebBrowserOrRunningTest() + 28
    frame #5: 0x00000001b0917530 WebKit`WebKit::WebsiteDataStoreConfiguration::WebsiteDataStoreConfiguration(WebKit::IsPersistent, WebKit::WebsiteDataStoreConfiguration::ShouldInitializePaths) + 136
    frame #6: 0x00000001b07e7e44 WebKit`WebKit::WebsiteDataStore::defaultDataStore() + 164
    frame #7: 0x00000001b07e7d48 WebKit`+[WKWebsiteDataStore defaultDataStore] + 28
    frame #8: 0x00000001b07e7cf4 WebKit`-[WKWebViewConfiguration websiteDataStore] + 40
    frame #9: 0x00000001b07e507c WebKit`-[WKWebView _initializeWithConfiguration:] + 92
    frame #10: 0x00000001b0886224 WebKit`-[WKWebView initWithFrame:configuration:] + 72
    frame #11: 0x00000001b0d98030 WebKit`-[WKWebView initWithFrame:] + 88
    frame #12: 0x000000010722116c InstrumentationDefault`specialized closure #1 in iOSVendorSystem.userAgent.getter [inlined] @nonobjc __C.WKWebView.init() -> __C.WKWebView at <compiler-generated>:0 [opt]
    frame #13: 0x0000000107221160 InstrumentationDefault`specialized closure #1 in iOSVendorSystem.userAgent.getter [inlined] __C.WKWebView.__allocating_init() -> __C.WKWebView at <compiler-generated>:0 [opt]
  * frame #14: 0x0000000107221154 InstrumentationDefault`specialized closure #1 in iOSVendorSystem.userAgent.getter at AppleUtils.swift:84:39 [opt]
    frame #15: 0x000000010725f90c InstrumentationDefault`thunk for @escaping @callee_guaranteed () -> () at <compiler-generated>:0 [opt]
    frame #16: 0x00000001070f0b98 libdispatch.dylib`_dispatch_call_block_and_release + 32
    frame #17: 0x00000001070f27bc libdispatch.dylib`_dispatch_client_callout + 20
    frame #18: 0x0000000107102d58 libdispatch.dylib`_dispatch_main_queue_drain + 1084
    frame #19: 0x000000010710290c libdispatch.dylib`_dispatch_main_queue_callback_4CF + 44
    frame #20: 0x000000019b5cb710 CoreFoundation`__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16
    frame #21: 0x000000019b5c8914 CoreFoundation`__CFRunLoopRun + 1996
    frame #22: 0x000000019b5c7cd8 CoreFoundation`CFRunLoopRunSpecific + 608
    frame #23: 0x00000001e04781a8 GraphicsServices`GSEventRunModal + 164
    frame #24: 0x000000019dc0090c UIKitCore`-[UIApplication _run] + 888
    frame #25: 0x000000019dcb49d0 UIKitCore`UIApplicationMain + 340
    frame #26: 0x000000019f7b8148 SwiftUI`___lldb_unnamed_symbol74307 + 168
    frame #27: 0x000000019f764714 SwiftUI`___lldb_unnamed_symbol71237 + 152
    frame #28: 0x000000019f7704d0 SwiftUI`___lldb_unnamed_symbol71675 + 132
    frame #29: 0x0000000104e2def4 Hubstaff`main [inlined] static Hubstaff.HubstaffApp.$main() -> () at HubstaffApp.swift:0 [opt]
    frame #30: 0x0000000104e2dec0 Hubstaff`main at HubstaffApp.swift:0 [opt]
    frame #31: 0x00000001bec79e4c dyld`start + 2240

[bsneed]

Thanks @lhunath! This change here would fix that:

#341

We've got some other stuff in progress, once it lands it'll all get released.