feats: better error handling for well known did genesis (#69)

## fixes KILTProtocol/ticket#No_ticket

@aybarsayan had imported his mnemonic from Sporran and was having
trouble generating a **well-known-did-config** because his DID keys on
the chain where different than the ones derivated on the project.

There was an error popping up that did not explained much. Now the
error(s) explains more.

backend/src/config.ts

@@ -61,7 +61,7 @@ async function deduceAccountAddress(): Promise<string> {
  *
  * @param didDocument
  */
-async function validateOurKeys(didDocument: Kilt.DidDocument) {
+export async function validateOurKeys(didDocument: Kilt.DidDocument) {
   const localKeyPairs = generateKeyPairs(DAPP_DID_MNEMONIC)
 
   // A DID can have several keys of type 'keyAgreement', but only up to one key of each of the other types.

scripts/genesisWellKnownDidConfig.ts

@@ -5,6 +5,9 @@ import path from 'path'
 import * as Kilt from '@kiltprotocol/sdk-js'
 import dotenv from 'dotenv'
 
+import { validateOurKeys } from '../backend/src/config'
+import { fetchDidDocument } from '../backend/src/utils/fetchDidDocument'
+
 import { generateAccount } from './launchUtils/generateAccount'
 import { generateKeyPairs } from './launchUtils/generateKeyPairs'
 import { VerifiableDomainLinkagePresentation } from './launchUtils/types'
@@ -142,6 +145,10 @@ async function main() {
   const dAppsDidKeys = generateKeyPairs(dAppMnemonic)
   const dappAccount = generateAccount(fundsMnemonic)
 
+  // Check that the DID keys saved on the blockchain match the one being derived from your mnemonic
+  const ourDidDocumentOnChain = await fetchDidDocument()
+  await validateOurKeys(ourDidDocumentOnChain)
+
   // Writes the attestation on the blockchain
   await selfAttestCredential(
     domainCredential,

scripts/wellKnownDIDConfiguration.ts

@@ -285,9 +285,16 @@ export async function selfAttestCredential(
   const result = await Kilt.Blockchain.signAndSubmitTx(
     submitTx,
     submitterAccount
-  )
+  ).catch((reason) => {
+    throw new Error(
+      'Could not sing and submit transaction:' +
+        JSON.stringify(reason, null, 2) +
+        '\n' +
+        'Make sure the keys saved on chain match the ones being derived from your mnemonic on this projects.'
+    )
+  })
 
-  if (result.isError) {
+  if (result?.isError) {
     throw new Error('Attestation failed')
   } else {
     console.log('Attestation successful')