constify missing catch cases

- ensure all missing catch cases are constant where possible

src/bitcoin-cli.cpp

@@ -94,7 +94,7 @@ static bool AppInitRPC(int argc, char* argv[])
     // Check for -testnet or -regtest parameter (BaseParams() calls are only valid after this clause)
     try {
         SelectBaseParams(ChainNameFromCommandLine());
-    } catch(std::exception &e) {
+    } catch (const std::exception& e) {
         fprintf(stderr, "Error: %s\n", e.what());
         return false;
     }

src/bitcoin-tx.cpp

@@ -37,7 +37,7 @@ static bool AppInitRawTx(int argc, char* argv[])
     // Check for -testnet or -regtest parameter (Params() calls are only valid after this clause)
     try {
         SelectParams(ChainNameFromCommandLine());
-    } catch(std::exception &e) {
+    } catch (const std::exception& e) {
         fprintf(stderr, "Error: %s\n", e.what());
         return false;
     }

src/bitcoind.cpp

@@ -109,7 +109,7 @@ bool AppInit(int argc, char* argv[])
         // Check for -testnet or -regtest parameter (Params() calls are only valid after this clause)
         try {
             SelectParams(ChainNameFromCommandLine());
-        } catch(std::exception &e) {
+        } catch (const std::exception& e) {
             fprintf(stderr, "Error: %s\n", e.what());
             return false;
         }

src/dbwrapper.h

@@ -104,7 +104,7 @@ public:
         try {
             CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
             ssKey >> key;
-        } catch(std::exception &e) {
+        } catch (const std::exception&) {
             return false;
         }
         return true;
@@ -120,7 +120,7 @@ public:
             CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
             ssValue.Xor(*obfuscate_key);
             ssValue >> value;
-        } catch(std::exception &e) {
+        } catch (const std::exception&) {
             return false;
         }
         return true;