Fixed JsonRpcProvider for pre-EIP-2930 chains (ethers-io#1766).

Author: ricmoo

packages/providers/src.ts/json-rpc-provider.ts

@@ -526,6 +526,24 @@ export class JsonRpcProvider extends BaseProvider {
     }
 
     async perform(method: string, params: any): Promise<any> {
+        // Legacy networks do not like the type field being passed along (which
+        // is fair), so we delete type if it is 0 and a non-EIP-1559 network
+        if (method === "call" || method === "estimateGas") {
+            const tx = params.transaction;
+            if (tx && tx.type != null && BigNumber.from(tx.type).isZero()) {
+                // If there are no EIP-1559 properties, it might be non-EIP-a559
+                if (tx.maxFeePerGas == null && tx.maxPriorityFeePerGas == null) {
+                    const feeData = await this.getFeeData();
+                    if (feeData.maxFeePerGas == null && feeData.maxPriorityFeePerGas == null) {
+                        // Network doesn't know about EIP-1559 (and hence type)
+                        params = shallowCopy(params);
+                        params.transaction = shallowCopy(tx);
+                        delete params.transaction.type;
+                    }
+                }
+            }
+        }
+
         const args = this.prepareRequest(method,  params);
 
         if (args == null) {