Addressed static analyzer warnings

GCDWebServer/Core/GCDWebServerRequest.m

@@ -88,7 +88,9 @@ NSString* const GCDWebServerRequestAttribute_RegexCaptures = @"GCDWebServerReque
 - (BOOL)open:(NSError**)error {
   int result = inflateInit2(&_stream, 15 + 16);
   if (result != Z_OK) {
-    *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+    if (error) {
+      *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+    }
     return NO;
   }
   if (![super open:error]) {
@@ -114,7 +116,9 @@ NSString* const GCDWebServerRequestAttribute_RegexCaptures = @"GCDWebServerReque
     _stream.avail_out = (uInt)maxLength;
     int result = inflate(&_stream, Z_NO_FLUSH);
     if ((result != Z_OK) && (result != Z_STREAM_END)) {
-      *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+      if (error) {
+        *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+      }
       return NO;
     }
     length += maxLength - _stream.avail_out;

GCDWebServer/Core/GCDWebServerResponse.m

@@ -94,7 +94,9 @@
 - (BOOL)open:(NSError**)error {
   int result = deflateInit2(&_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED, 15 + 16, 8, Z_DEFAULT_STRATEGY);
   if (result != Z_OK) {
-    *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+    if (error) {
+      *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+    }
     return NO;
   }
   if (![super open:error]) {
@@ -130,7 +132,9 @@
         if (result == Z_STREAM_END) {
           _finished = YES;
         } else if (result != Z_OK) {
-          *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+          if (error) {
+            *error = [NSError errorWithDomain:kZlibErrorDomain code:result userInfo:nil];
+          }
           return nil;
         }
         length += maxLength - _stream.avail_out;

GCDWebServer/Requests/GCDWebServerDataRequest.m

@@ -51,7 +51,9 @@
     _data = [[NSMutableData alloc] init];
   }
   if (_data == nil) {
-    *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed allocating memory"}];
+    if (error) {
+      *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed allocating memory"}];
+    }
     return NO;
   }
   return YES;

GCDWebServer/Requests/GCDWebServerFileRequest.m

@@ -56,7 +56,9 @@
 - (BOOL)open:(NSError**)error {
   _file = open([_temporaryPath fileSystemRepresentation], O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
   if (_file <= 0) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     return NO;
   }
   return YES;
@@ -64,7 +66,9 @@
 
 - (BOOL)writeData:(NSData*)data error:(NSError**)error {
   if (write(_file, data.bytes, data.length) != (ssize_t)data.length) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     return NO;
   }
   return YES;
@@ -72,7 +76,9 @@
 
 - (BOOL)close:(NSError**)error {
   if (close(_file) < 0) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     return NO;
   }
 #ifdef __GCDWEBSERVER_ENABLE_TESTING__

GCDWebServer/Requests/GCDWebServerMultiPartFormRequest.m

@@ -376,7 +376,9 @@ static NSData* _dashNewlineData = nil;
   NSString* boundary = GCDWebServerExtractHeaderValueParameter(self.contentType, @"boundary");
   _parser = [[GCDWebServerMIMEStreamParser alloc] initWithBoundary:boundary defaultControlName:nil arguments:_arguments files:_files];
   if (_parser == nil) {
-    *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed starting to parse multipart form data"}];
+    if (error) {
+      *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed starting to parse multipart form data"}];
+    }
     return NO;
   }
   return YES;
@@ -384,7 +386,9 @@ static NSData* _dashNewlineData = nil;
 
 - (BOOL)writeData:(NSData*)data error:(NSError**)error {
   if (![_parser appendBytes:data.bytes length:data.length]) {
-    *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed continuing to parse multipart form data"}];
+    if (error) {
+      *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed continuing to parse multipart form data"}];
+    }
     return NO;
   }
   return YES;
@@ -394,7 +398,9 @@ static NSData* _dashNewlineData = nil;
   BOOL atEnd = [_parser isAtEnd];
   _parser = nil;
   if (!atEnd) {
-    *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed finishing to parse multipart form data"}];
+    if (error) {
+      *error = [NSError errorWithDomain:kGCDWebServerErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey: @"Failed finishing to parse multipart form data"}];
+    }
     return NO;
   }
   return YES;

GCDWebServer/Responses/GCDWebServerFileResponse.m

@@ -142,11 +142,15 @@ static inline NSDate* _NSDateFromTimeSpec(const struct timespec* t) {
 - (BOOL)open:(NSError**)error {
   _file = open([_path fileSystemRepresentation], O_NOFOLLOW | O_RDONLY);
   if (_file <= 0) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     return NO;
   }
   if (lseek(_file, _offset, SEEK_SET) != (off_t)_offset) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     close(_file);
     return NO;
   }
@@ -158,7 +162,9 @@ static inline NSDate* _NSDateFromTimeSpec(const struct timespec* t) {
   NSMutableData* data = [[NSMutableData alloc] initWithLength:length];
   ssize_t result = read(_file, data.mutableBytes, length);
   if (result < 0) {
-    *error = GCDWebServerMakePosixError(errno);
+    if (error) {
+      *error = GCDWebServerMakePosixError(errno);
+    }
     return nil;
   }
   if (result > 0) {