diff --git a/src/group-signing-panacea-client.spec.ts b/src/group-signing-panacea-client.spec.ts
index bd18b27..373162e 100644
--- a/src/group-signing-panacea-client.spec.ts
+++ b/src/group-signing-panacea-client.spec.ts
@@ -6,6 +6,7 @@ import { v4 as uuidv4 } from "uuid";
 import { TextEncoder } from "util";
 import Long from "long";
 import { Secp256k1HdWallet } from "@cosmjs/amino";
+import assert from "assert";
 
 describe("GroupSigningPanaceaClient", () => {
   pendingWithoutPanacead();
@@ -93,6 +94,7 @@ describe("GroupSigningPanaceaClient", () => {
         expect(res).toBeTruthy();
 
         const record = await client.getPanaceaClient().getRecord(ownerAddress, topicName, Long.fromInt(0));
+        assert(record);
         expect(record.writerAddress).toEqual(writerAddress);
         expect(record.key).toEqual(key);
         expect(record.value).toEqual(value);
diff --git a/src/group-signing-panacea-client.ts b/src/group-signing-panacea-client.ts
index 0c6293d..5ccbb34 100644
--- a/src/group-signing-panacea-client.ts
+++ b/src/group-signing-panacea-client.ts
@@ -106,8 +106,10 @@ export class GroupSigningPanaceaClient extends SigningPanaceaClient {
     memo: string,
     explicitSignerDatas?: SignerData[],
   ): Promise<TxRaw> {
-    let signerDatas: SignerData[] = explicitSignerDatas;
-    if (!signerDatas) {
+    let signerDatas: SignerData[];
+    if (explicitSignerDatas) {
+      signerDatas = explicitSignerDatas;
+    } else {
       // Retrieve 'SignerData's from the chain.
       const chainId = await this.getChainId();
       signerDatas = await Promise.all(
diff --git a/src/signing-panacea-client.spec.ts b/src/signing-panacea-client.spec.ts
index 159e1a6..250ed7b 100644
--- a/src/signing-panacea-client.spec.ts
+++ b/src/signing-panacea-client.spec.ts
@@ -8,6 +8,7 @@ import { DIDDocument } from "./proto/panacea/did/v2/did";
 import { isBroadcastTxSuccess } from "@cosmjs/stargate";
 import { Secp256k1 } from "./crypto/secp256k1";
 import { DidUtil } from "./did/util";
+import assert from "assert";
 
 describe("SigningPanaceaClient", () => {
   pendingWithoutPanacead();
@@ -51,6 +52,7 @@ describe("SigningPanaceaClient", () => {
         expect(res).toBeTruthy();
 
         const topic = await client.getPanaceaClient().getTopic(ownerAddress, topicName);
+        assert(topic);
         expect(topic.description).toEqual("description!");
       });
     });
@@ -62,6 +64,7 @@ describe("SigningPanaceaClient", () => {
         expect(res).toBeTruthy();
 
         const writer = await client.getPanaceaClient().getWriter(ownerAddress, topicName, writerAddress);
+        assert(writer);
         expect(writer.moniker).toEqual("jack");
         expect(writer.description).toEqual("hello");
       });
@@ -82,6 +85,7 @@ describe("SigningPanaceaClient", () => {
         expect(res).toBeTruthy();
 
         const record = await client.getPanaceaClient().getRecord(ownerAddress, topicName, Long.fromInt(0));
+        assert(record);
         expect(record.writerAddress).toEqual(writerAddress);
         expect(record.key).toEqual(key);
         expect(record.value).toEqual(value);
@@ -128,6 +132,7 @@ describe("SigningPanaceaClient", () => {
       expect(isBroadcastTxSuccess(res)).toBeTruthy();
 
       const didDocumentWithSeq = await client.getPanaceaClient().getDid(didDocument.id);
+      assert(didDocumentWithSeq);
       expect(didDocumentWithSeq.document).toEqual(didDocument);
     });
 
@@ -155,6 +160,7 @@ describe("SigningPanaceaClient", () => {
         expect(isBroadcastTxSuccess(res)).toBeTruthy();
 
         const didDocumentWithSeq = await client.getPanaceaClient().getDid(didDocument.id);
+        assert(didDocumentWithSeq);
         expect(didDocumentWithSeq.document).toEqual(didDocument);
       });
 
diff --git a/src/signing-panacea-client.ts b/src/signing-panacea-client.ts
index c36c37a..8c27535 100644
--- a/src/signing-panacea-client.ts
+++ b/src/signing-panacea-client.ts
@@ -113,8 +113,8 @@ export class SigningPanaceaClient extends SigningStargateClient {
     super(tmClient, signer, options);
 
     // Build a PanaceaFeeTable
-    const { panaceaGasLimits = panaceaDefaultGasLimits } = options; // Use the default one, if not specified
-    this.panaceaFees = buildFeeTable(options.gasPrice, panaceaDefaultGasLimits, panaceaGasLimits)
+    const { gasPrice = panaceaDefaultGasPrice, panaceaGasLimits = panaceaDefaultGasLimits } = options; // Use the default one, if not specified
+    this.panaceaFees = buildFeeTable(gasPrice, panaceaDefaultGasLimits, panaceaGasLimits)
   }
 
   /**
diff --git a/tsconfig.json b/tsconfig.json
index 762e53d..ce91f1a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -22,18 +22,17 @@
     "removeComments": true,                   /* Do not emit comments to output. */
     // "noEmit": true,                        /* Do not emit outputs. */
     // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
-     "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+    "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
     // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
 
     /* Strict Type-Checking Options */
     "strict": true,                           /* Enable all strict type-checking options. */
-    "noImplicitAny": true,                    /* Raise error on expressions and declarations with an implied 'any' type. */
-    //TODO: to be true, after making all codes type-safe
-    "strictNullChecks": false,                /* Enable strict null checks. */
+    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,              /* Enable strict null checks. */
     // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
     // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
     // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
-    "noImplicitThis": true,                   /* Raise error on 'this' expressions with an implied 'any' type. */
+    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
     // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
 
     /* Additional Checks */