Custom runtime module errors (#3433)

* srml-system checks

* wip

* more modules compiles

* node-runtime checks

* build.sh passes

* include dispatch error in failed event

* revert some unnecessary changes

* refactor based on comments

* more compile error fixes

* avoid unnecessary into

* reorder code

* fixes some tests

* manually implement encode & decode to avoid i8 workaround

* more test fixes

* more fixes

* more error fixes

* Apply suggestions from code review

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* address comments

* test for DispatchError encoding

* tyep alias for democracy

* make error printable

* line width

* fix balances tests

* fix executive test

* fix system tests

* bump version

* ensure consistent method signature

* Apply suggestions from code review

Co-Authored-By: Gavin Wood <github@gavwood.com>

* changes based on review

* Add issue number for TODOs

* fix

* line width

* fix test

* Update core/sr-primitives/src/lib.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update core/sr-primitives/src/traits.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update srml/council/src/motions.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update srml/council/src/motions.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* update based on review

* More concrete macro matching

* fix test build issue

* Update hex-literal dependency version. (#3141)

* Update hex-literal dep version.

* Update lock file.

* Start to rework the new error handling

* More work to get it back compiling

* Start to fix after master merge

* The great transaction error handling refactoring

* Make `decl_error` errors convertible to `&'static str`

* Make srml-executive build again

* Fix `sr-primitives` tests

* More fixes

* Last round of fix ups

* Fix build

* Fix build

* Apply suggestions from code review

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Rename some stuff

* Fixes after master merge

* Adds `CheckBlockGasLimit` signed extension

* Remove debug stuff

* Fix srml-balances test

* Rename `InvalidIndex` to `CannotLookup`

* Remove weird generic parameters

* Rename function again

* Fix import

* Document the signed extension

* Change from `Into` to `From`

* Update srml/contracts/src/lib.rs

Co-Authored-By: Sergei Pepyakin <sergei@parity.io>

* Fix compilation

* Update srml/contracts/src/lib.rs

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Update core/sr-primitives/src/transaction_validity.rs

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Remove unused code

* Fix compilation

* Some cleanups

* Fix compile errors

* Make `TransactionValidity` a `Result`

* Apply suggestions from code review

Co-Authored-By: Gavin Wood <gavin@parity.io>

* Beautify the code a little bit and fix test

* Make `CannotLookup` an inherent error declared by `decl_error!`

* Adds some documentation

* Make `ApplyOutcome` a result

* Up the spec_version

* Apply suggestions from code review

Co-Authored-By: Gavin Wood <gavin@parity.io>
Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

substrate/srml/indices/src/lib.rs

@@ -19,10 +19,10 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use rstd::{prelude::*, result, marker::PhantomData, convert::TryInto};
+use rstd::{prelude::*, marker::PhantomData, convert::TryInto};
 use codec::{Encode, Codec};
 use support::{StorageValue, StorageMap, Parameter, decl_module, decl_event, decl_storage};
-use sr_primitives::traits::{One, SimpleArithmetic, StaticLookup, Member};
+use sr_primitives::traits::{One, SimpleArithmetic, StaticLookup, Member, LookupError};
 use system::{IsDeadAccount, OnNewAccount};
 
 use self::address::Address as RawAddress;
@@ -224,9 +224,11 @@ impl<T: Trait> OnNewAccount<T::AccountId> for Module<T> {
 impl<T: Trait> StaticLookup for Module<T> {
 	type Source = address::Address<T::AccountId, T::AccountIndex>;
 	type Target = T::AccountId;
-	fn lookup(a: Self::Source) -> result::Result<Self::Target, &'static str> {
-		Self::lookup_address(a).ok_or("invalid account index")
+
+	fn lookup(a: Self::Source) -> Result<T::AccountId, LookupError> {
+		Self::lookup_address(a).ok_or(LookupError)
 	}
+
 	fn unlookup(a: Self::Target) -> Self::Source {
 		address::Address::Id(a)
 	}