better warning msg

libs/remix-core-plugin/src/lib/compiler-fetch-and-compile.ts

@@ -72,13 +72,16 @@ export class FetchAndCompile extends Plugin {
     try {
       data = await fetchContractFromSourcify(this, network, contractAddress, targetPath)
     } catch (e) {
+      this.call('notification', 'toast', e.message)
       console.log(e) // and fallback to getting the compilation result from etherscan
     }
 
     if (!data) {
+      this.call('notification', 'toast', `contract ${contractAddress} not found in Sourcify, checking in Etherscan..`)
       try {
         data = await fetchContractFromEtherscan(this, network, contractAddress, targetPath)
       } catch (e) {
+        this.call('notification', 'toast', e.message)
         setTimeout(_ => this.emit('notFound', contractAddress), 0) // plugin framework returns a time out error although it actually didn't find the source...
         this.unresolvedAddresses.push(contractAddress)
         return localCompilation()    

libs/remix-core-plugin/src/lib/helpers/fetch-etherscan.ts

@@ -16,7 +16,7 @@ export const fetchContractFromEtherscan = async (plugin, network, contractAddres
         }
       } 
     } else throw new Error('unable to retrieve contract data ' + data.message)
-  }
+  } else throw new Error('unable to try fetching the source code from etherscan: etherscan access token not found. please go to the Remix settings page and provide an access token.')
 
   if (!data || !data.result) {
     return null

libs/remix-core-plugin/src/lib/helpers/fetch-sourcify.ts

@@ -5,7 +5,7 @@ export const fetchContractFromSourcify = async (plugin, network, contractAddress
   try {
     data = await plugin.call('sourcify', 'fetchByNetwork', contractAddress, network.id)
   } catch (e) {
-    console.log(e) // and fallback to getting the compilation result from etherscan
+    console.log(e)
   }
 
   if (!data || !data.metadata) {

libs/remix-ui/debugger-ui/src/lib/debugger-ui.tsx

@@ -91,7 +91,7 @@ export const DebuggerUI = (props: DebuggerUIProps) => {
       if (!lineColumnPos) {        
         await debuggerModule.discardHighlight()
         setState(prevState => {
-          return { ...prevState, sourceLocationStatus: 'Source location not available.' }
+          return { ...prevState, sourceLocationStatus: 'Source location not available, neither in Sourcify nor in Etherscan. Please make sure the etherscan access token is provided in the settings.' }
         })
         return
       }