Error map
type 'Null' is not a subtype of type 'String' Dart: type 'Null' is not a subtype of type 'String' in type cast
Flutter / Dart · layer 1, On your device
Centre: this error. First ring: errors it is linked with (9). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (9)
Dart/Flutter: Null check operator used on a null value
The ! operator was applied to a variable that was null at runtime.
Dart: LateInitializationError: Field 'controller' has not been initialized
A `late` variable was read before it was assigned.
Dart: Non-nullable instance field 'name' must be initialized. Try adding an initializer expression, or a generative constructor that initializes it, or mark it 'late'
With null safety every non-nullable field needs a value by the end of construction.
Dart: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>' in type cast
JSON decoded to a Map but your code expected a List (or the other way round).
Dart: Bad state: No element — .first, .last or .single on an empty list
You called `.first`, `.last`, `.single` or `.reduce` on an empty collection.
Dart: RangeError (index): Invalid value: Valid value range is empty: 0
A list or string was indexed outside its bounds, often an empty list or an off-by-one in `itemBuilder`.
Dart: FormatException: Unexpected character (at character 1) <!DOCTYPE html> — jsonDecode of an HTML page
`jsonDecode` received something that is not JSON, commonly an HTML error page, an empty string, or a plain-text message.
Dart: The property 'length' can't be unconditionally accessed because the receiver can be 'null'
With null safety you used `.` on a nullable value; Dart requires a null check first.
Dart: The named parameter 'key' is required, but there's no corresponding argument
A constructor or function marked `required` for a parameter was called without it.
Two steps away (11)
Flutter: A RenderFlex overflowed by x pixels on the right/bottom
A Row or Column’s children need more space than available, so Flutter draws the yellow-black overflow stripes.
Flutter: setState() called after dispose(): _MyState#1a2b3 (lifecycle state: defunct, not mounted)
An async callback (network, timer, stream) finished after the widget was removed and then called setState.
TS2322: Type 'X' is not assignable to type 'Y'
You assigned a value whose type doesn’t match the declared type of the variable, property or return value.
Dart: The argument type 'String?' can't be assigned to the parameter type 'String'
You passed a value whose type does not match what the function parameter requires.
Dart: The getter 'name' isn't defined for the type 'User' / The method 'foo' isn't defined for the class
The analyzer cannot find that property or method on the object's static type.
Dart: Error: Couldn't resolve the package 'x' in 'package:x/x.dart'
Code imports a package that is not in `pubspec.yaml` or `pub get` has not been run since adding it.
Dart: Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:async' Class: _Future@4048458
You tried to send an object (closure, Future, socket, platform object) to another isolate that cannot be copied.
Dart: Bad state: Stream has already been listened to
A single-subscription stream was listened to twice, for instance by two `StreamBuilder`s or after a rebuild.
Flutter: Unhandled Exception: SocketException: Failed host lookup: 'api.example.com' (OS Error: No address associated with hostname, errno = 7)
The app could not resolve or reach the server: no internet, wrong host name, DNS failure, or missing network permission.
Flutter (Android): java.io.IOException: Cleartext HTTP traffic to api.example.com not permitted
Android 9+ blocks plain `http://` requests by default; the app must use HTTPS or explicitly allow cleartext for that host.
Dart pub: Because app depends on intl ^0.19.0 and flutter_localizations from sdk depends on intl 0.18.1, version solving failed
`flutter pub get` cannot find a set of package versions that satisfy every dependency's constraints.
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