[Request] Improve error message when DID cannot be resolved

[jmcanterafonseca-iota]

Bug description

Try to resolve an Identity such as did:iota:dev:DfdEgjf1MQbh23QHAZwRpUtrTknf6BFk4MrXQMv7hQbG on the mainnet

An error such as the one below is raised, not informative nor helpful

Error: Error [ChainError]: Chain Error: Invalid Root Document
    at module.exports.__wbg_new_342a24ca698edd87 (/Users/jmcanterafonseca/work/IOTA/develop/tangle.js/tools/tangle-cli/node_modules/@iota/identity-wasm/node/identity_wasm.js:2884:15)
    at <anonymous>:wasm-function[4054]:0x1ade22
    at <anonymous>:wasm-function[3455]:0x19d68e
    at <anonymous>:wasm-function[1543]:0x13da21
    at <anonymous>:wasm-function[1160]:0x11c421
    at <anonymous>:wasm-function[3096]:0x190fac
    at <anonymous>:wasm-function[2592]:0x17cd4e
    at _dyn_core__ops__function__FnMut__A____Output___R_as_wasm_bindgen__closure__WasmClosure___describe__invoke__hca1c949258eb7ac8 (<anonymous>:wasm-function[5764]:0x1c886b)
    at __wbg_adapter_32 (/Users/jmcanterafonseca/work/IOTA/develop/tangle.js/tools/tangle-cli/node_modules/@iota/identity-wasm/node/identity_wasm.js:214:10)
    at real (/Users/jmcanterafonseca/work/IOTA/develop/tangle.js/tools/tangle-cli/node_modules/@iota/identity-wasm/node/identity_wasm.js:199:20)

Language version

WASM bindings 0.4.0

Expected behaviour

A controlled error informing that the Identity cannot be resolved

Actual behaviour

A not controlled error that reveals internal working details of the library

[cycraig]

The error messages should be more descriptive with the changes in #506 and #512. This should be included in the next release.

Examples:

The common cases are as follows:

1. From your example, trying to resolve a DID using a Client configured for a different network will now throw the following error:

   Err > DIDNotFound: DID network 'dev' does not match client network 'main'
   

2. Trying to resolve a non-existent DID or one that has been pruned from the node will throw:

   Err > DIDNotFound: DID not found or pruned
   

3. Trying to resolve a DID whose root document is invalid, e.g. was not signed correctly or otherwise violates the method specification:

   Err > DIDNotFound: no valid root document found